Manufacturers of corrugated paper products, known as Box Makers, produce both foldable boxes which have been folded and glued at the factory and die cut flat sheets which may be used either in their flat state or folded into a desired shape. These will be referred to as folded boxes and flat boxes respectively. The term boxes alone can refer to both folded and flat boxes.
Both the folded boxes and the flat boxes are produced by Converting machinery which processes the Corrugated Sheet Stock produced by the machinery known as a Corrugator. The Corrugated Sheet Stock is corrugated material cut to a specific size with optional scoring. Scoring is the intentional crushing of the corrugated flutes in order to allow folding of the corrugated material. However, the Corrugated Sheet Stock has not been cut or notched to the detail typically required to produce the final foldable boxes or the flat boxes.
Often customized printing is required on boxes which may be done by 1) using a preprinted material integrated into the Corrugated Sheet Stock on the Corrugator, 2) using flexographic printing during the Converting process or 3) applying ink or labels post Converting through various techniques.
During the Converting process the Corrugated Sheet Stock is transformed into a box by performing additional cutting and optionally adding scoring and printing. There are multiple possible purposes for the additional cutting of the Corrugated Sheet Stock. Many of these cutting operations will result in pieces of the original Corrugated Sheet Stock being completely separated from the final box. These pieces are in general referred to as Scrap.
In order to achieve to proper registration of the printing and the edges of the box the Corrugated Sheet Stock may be oversized slightly so that some or all of the perimeter is trimmed during the Converting process. This results in what is being defined as Edge Trim Scrap. The Corrugated Sheet Stock is moving in a flow direction during the Converting process and thus Lead Edge Trim Scrap is the Scrap along the entire front edge of the Corrugated Sheet Stock, first to be processed by the Converting machinery. Trail Edge Trim Scrap is the Scrap along the entire back edge of the Corrugated Sheet Stock, last to be processed. Side Edge Trim Scrap is produced on both sides of the Corrugated Sheet Stock. Slot Scrap is a common relatively long but narrow type of Scrap which when removed allows boxes to be folded properly. All other Scrap will be referred to as Internal Scrap and can come in many sizes and shapes.
If the Scrap is cut complete free from the box and the Ejecting Rubber completely dislodges the Scraps from the box, the Scrap is referred to as Loose Scrap. If Internal Scrap is cut completely free from the box but the Ejecting Rubber fails to dislodge the Scraps from the Box, the Scrap is referred to as Trapped Scrap. If the Scrap is not cut completely free from the box and the Ejecting Rubber fails to tear the Scrap from the box, the Scrap is often attached by a minimal amount of paper hanging onto the box by a thread and is referred to as Hanging Chads. The amount of residual paper connecting the Hanging Chad to the box determines the Hanging Chad Strength which is defined as the pulling force required to tear the Hanging Chad from the Box. There may also be other types of Scrap.
As the boxes are produced there are a variety of methods to form Stacks of the boxes which in turn are sold to other companies which will be referred to as the Box Customer. There are a multitude of applications for these boxes and there are many reasons why it is undesirable for the Scrap to be included in shipment to the Box Customer. Erecting of the box is the process of taking the box and manipulating it by folding, bending, interlocking, stapling, taping, etc. in order for the box to be ready for its final usage. For Box Customers that manually erect their Boxes, the inclusion of Scrap is undesirable because of the additional mess created. For Box Customers that use automatic machinery to erect their Boxes, the Scrap can lead to jams in their machinery causing undesirable downtime and lower production. For Box Customers that use the box for food, such as a pizza box, having Scrap included in the final erected box is clearly undesirable.
In the conversion of the Corrugated Sheet Stock into Boxes the material is fed through machinery. The Lead Edge for both Corrugated Sheet Stock and Boxes refers to the first edge of travel across the machine whereas the Trailing Edge refers to the last edge of travel across the machine. The Corrugated Sheet Stock may be cut completely in the cross-machine direction in one or more locations to create two or more boxes in the through-machine direction. These are referred to as Ups. The Corrugated Sheet Stock may be cut completely in the through-machine direction in one or more locations to create two or more boxes in the cross-machine direction. These are referred to as Outs.
There are multiple methods by which the cutting of the Corrugated Sheet Stock may be accomplished during the Converting process. One example method for cutting Corrugated Sheet Stock is known as Rotary Die Cutting. A typical configuration of a Rotary Die Cutter, known as Rule and Rubber, uses of a pair of cylinders where the lower cylinder, known as the Anvil, is covered in a firm but soft rubber material and the top cylinder is mounted with a Die Board. The Die Board is normally a curved plywood base in which embedded are a customized set of steel Rules, which protrude from the plywood base and when rotated with the Anvil will cut and score the Corrugated Sheet Stock into the final desired box. The actual cutting of the box occurs where the tangent of the Die Board meets the tangent of the Anvil. Since there is a finite distance over which cutting occurs, the region of cutting and Die Board control is referred to as the Die Board Control Zone. Ejecting Rubber is located on the plywood base of the Die Board between the rules in order to eject the Scrap as the boxes emerge from the nip point of the Die Board and the Anvil. The path of the box between the Die Board and the Anvil is theoretically horizontal and is known as the Board Line. However, in reality the box may vary from the Board Line as it exits the Rotary Die Cutter, due to warp of the Corrugated Sheet Stock and the potential sticking or over-ejecting by the Die Board. The transportation speed of the box, as determined by the effective linear speed at the nip of the Die Board and Anvil, is known as Line Speed. Also relevant would be the similar process of steel-on-on steel Rotary Die Cutting. The Rotary Die Cutting process is relevant since there is not an integral method in the process for positive separation of the Scrap from the box.
A box that has been Die Cut commonly has cutting and scoring such that when folded a corner is naturally formed. When in flat form, the corner is a peninsula of corrugated material at the corner of the box, and referred to as a Flap. Since the Flaps are partially cut from the main body of the box, they are less rigid, require better support during transportation and are more easily bent backwards.
The foldable box is typically produced by a system referred to in the industry as a Flexo Folder Gluer. This may include Rotary Die Cutting or Slotting-Scoring. The Flat Box is typically produced by either a Rotary Die Cutter (which includes Rotary Die Cutting) or by a Flat Bed Die Cutter.
For the purposes of this document, the term Press will refer to the machinery that feeds, prints and cuts the Corrugated Sheet Stock to produce the final boxes.
The Box Makers typically have many customers and a wide variety of different style of boxes which need to be produced. They need to set up and run many different orders during a given production period. The Box Maker is highly motivated to reduce the time used for setting up a new order. This is known as Order Setup Time.
The Box Maker often will setup and run an order initially and then need to repeat running of the order multiple times periodically in the future. There is value to the Box Maker in providing the ability to setup faster for a repeat order by returning to the configuration specified by the operator the last time the order ran. This is known is Repeat Order Setup.
The quality of the box surface and print quality is an important factor to the Box Maker. Any process that damages the actual surface of the corrugated material or reduces the quality of the printing by smearing or marking can result in unsellable boxes or boxes of lower value. Many Layboy applications involve sandwiching the box as it is being conveyed. Excessive pressure on the box can create permanent crushing of the box flutes which is known as False Scoring. Exposing a printed surface of the box to a conveying surface with a significant combination of relative velocity and pressure can damage the print which is known as Print Damage.